feat: implement agent-notify CLI with hooks and tmux passthrough

Add OSC 777 notification sender, Cursor/Claude hook adapters,
config/install commands, and README for Ghostty + tmux setup.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/config/config.go

@@ -0,0 +1,102 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/BurntSushi/toml"
+)
+
+type Config struct {
+	Events Events `toml:"events"`
+	Notify Notify `toml:"notify"`
+}
+
+type Events struct {
+	Stop bool `toml:"stop"`
+	Idle bool `toml:"idle"`
+	Tool bool `toml:"tool"`
+}
+
+type Notify struct {
+	Protocol      string `toml:"protocol"`
+	TitleTemplate string `toml:"title_template"`
+	BodyStop      string `toml:"body_stop"`
+	BodyIdle      string `toml:"body_idle"`
+	BodyTool      string `toml:"body_tool"`
+}
+
+func Default() Config {
+	return Config{
+		Events: Events{Stop: true, Idle: false, Tool: false},
+		Notify: Notify{
+			Protocol:      "osc777",
+			TitleTemplate: "{agent} — {context}",
+			BodyStop:      "等待输入",
+			BodyIdle:      "空闲 60s+，等待输入",
+			BodyTool:      "工具执行完成",
+		},
+	}
+}
+
+func DefaultPath() string {
+	return filepath.Join(os.Getenv("HOME"), ".config", "agent-notify", "config.toml")
+}
+
+func Load(path string) (Config, error) {
+	cfg := Default()
+	if path == "" {
+		return cfg, nil
+	}
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return cfg, nil
+	}
+	if _, err := toml.DecodeFile(path, &cfg); err != nil {
+		return Config{}, err
+	}
+	return cfg, nil
+}
+
+func LoadDefault() (Config, error) {
+	return Load(DefaultPath())
+}
+
+func (c Config) EventEnabled(event string) bool {
+	switch strings.ToLower(event) {
+	case "stop":
+		return c.Events.Stop
+	case "idle":
+		return c.Events.Idle
+	case "tool":
+		return c.Events.Tool
+	default:
+		return false
+	}
+}
+
+func (c Config) BodyForEvent(event string) string {
+	switch strings.ToLower(event) {
+	case "idle":
+		return c.Notify.BodyIdle
+	case "tool":
+		return c.Notify.BodyTool
+	default:
+		return c.Notify.BodyStop
+	}
+}
+
+func (c Config) WriteDefault(path string) error {
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return err
+	}
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0644)
+	if err != nil {
+		if os.IsExist(err) {
+			return nil
+		}
+		return err
+	}
+	defer f.Close()
+	return toml.NewEncoder(f).Encode(Default())
+}